Is it possible to transform a flat surface into a paraboloid
$$z=x^2+y^2$$
such that there is no strain in the circular in the circular cross section (direction vector A)?
If the answer is yes, is it possible to calculate the shape of such a flat surface?
Where can I find more information to solve this kind of problems?

Since it seems my solution is what the OP wanted...
Consider the parametric equations
$$\begin{align*} x&=cu\cos\,\theta\\ y&=cu\sin\,\theta\\ z&=h(1-u^2) \end{align*}$$
with the parameter ranges $0\leq u\leq 1$ and $0\leq\theta\leq2\pi$.
For $h=0$, you have a disk of radius $c$; from here, varying $h$ in either the positive or negative directions will yield a paraboloid of revolution: